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Written by Fedja Drndarski
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Monday, 16 March 2009 |
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Page 2 of 7
Specimen that we got had locked multiplier and we managed to overclock it at 3.8GHz. To achieve these values of HTT bus, good motherboard that has good overclocking pedigree and BIOS according to that reputation (that can set clock of northbridge, memory timings and voltages) is essential equipment. Since we got locked CPU, NB/L3 voltage wasn’t possible to set higher than 1.3V, but this is enough to achieve solid 2.5GHz for NB/L3. Our best guess is that overclock results are much higher than this, but for stable overclock we needed more voltage and for such extreme results we must wait for Black Edition.
Next problem that we had with locked multiplier of our test CPU was inability to extract maximum performance levels from our memory modules. If we set memory at 800MHz in BIOS and use DDR2-1066 modules, maximum that could be expected is somewhere around 1100MHz despite the fact that same memory modules can operate even at 1200MHz. To achieve high CPU frequency we needed to lower memory frequency at 667 or 533MHz. If we set memory at 553MHz and set bus at 300MHz in BIOS result will be: CPU at 3.9GHz and only 800MHz for RAM. Since CPU won’t be stable at 3900MHz we needed to lower frequencies and end up with even lower memory clock. Optimal overclock for CPUs like this is between 3600 and 3650 MHz with memory set at 1100MHz and CL4 5-4-12 2T. CPU operated at only 1.4V and performances of system were much better compared to settings: 3800MHz for CPU, 667MHz for DDR2 at CL3 3-3-6 2T. All overclocked results were done at 3600MHz and system operated absolutely stable.
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Processors 
